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Add support for seamless DB upgrades / migrations (
--upgrade).
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -1 +0,0 @@ | ||
| dictpress | ||
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,147 @@ | ||
| package main | ||
|
|
||
| import ( | ||
| "fmt" | ||
| "strings" | ||
|
|
||
| "github.com/jmoiron/sqlx" | ||
| "github.com/knadh/dictpress/internal/migrations" | ||
| "github.com/knadh/koanf/v2" | ||
| "github.com/knadh/stuffbin" | ||
| "github.com/lib/pq" | ||
| "golang.org/x/mod/semver" | ||
| ) | ||
|
|
||
| // migFunc represents a migration function for a particular version. | ||
| // fn (generally) executes database migrations and additionally | ||
| // takes the filesystem and config objects in case there are additional bits | ||
| // of logic to be performed before executing upgrades. fn is idempotent. | ||
| type migFunc struct { | ||
| version string | ||
| fn func(*sqlx.DB, stuffbin.FileSystem, *koanf.Koanf) error | ||
| } | ||
|
|
||
| // migList is the list of available migList ordered by the semver. | ||
| // Each migration is a Go file in internal/migrations named after the semver. | ||
| // The functions are named as: v0.7.0 => migrations.V0_7_0() and are idempotent. | ||
| var migList = []migFunc{ | ||
| {"v2.0.0", migrations.V2_0_0}, | ||
| } | ||
|
|
||
| // upgrade upgrades the database to the current version by running SQL migration files | ||
| // for all version from the last known version to the current one. | ||
| func upgrade(db *sqlx.DB, fs stuffbin.FileSystem, prompt bool) { | ||
| if prompt { | ||
| var ok string | ||
| fmt.Printf("** IMPORTANT: Take a backup of the database before upgrading.\n") | ||
| fmt.Print("continue (y/n)? ") | ||
| if _, err := fmt.Scanf("%s", &ok); err != nil { | ||
| lo.Fatalf("error reading value from terminal: %v", err) | ||
| } | ||
| if strings.ToLower(ok) != "y" { | ||
| fmt.Println("upgrade cancelled") | ||
| return | ||
| } | ||
| } | ||
|
|
||
| _, toRun, err := getPendingMigrations(db) | ||
| if err != nil { | ||
| lo.Fatalf("error checking migrations: %v", err) | ||
| } | ||
|
|
||
| // No migrations to run. | ||
| if len(toRun) == 0 { | ||
| lo.Printf("no upgrades to run. Database is up to date.") | ||
| return | ||
| } | ||
|
|
||
| // Execute migrations in succession. | ||
| for _, m := range toRun { | ||
| lo.Printf("running migration %s", m.version) | ||
| if err := m.fn(db, fs, ko); err != nil { | ||
| lo.Fatalf("error running migration %s: %v", m.version, err) | ||
| } | ||
|
|
||
| // Record the migration version in the settings table. There was no | ||
| // settings table until v0.7.0, so ignore the no-table errors. | ||
| if err := recordMigrationVersion(m.version, db); err != nil { | ||
| if isTableNotExistErr(err) { | ||
| continue | ||
| } | ||
| lo.Fatalf("error recording migration version %s: %v", m.version, err) | ||
| } | ||
| } | ||
|
|
||
| lo.Printf("upgrade complete") | ||
| } | ||
|
|
||
| // checkUpgrade checks if the current database schema matches the expected | ||
| // binary version. | ||
| func checkUpgrade(db *sqlx.DB) { | ||
| lastVer, toRun, err := getPendingMigrations(db) | ||
| if err != nil { | ||
| lo.Fatalf("error checking migrations: %v", err) | ||
| } | ||
|
|
||
| // No migrations to run. | ||
| if len(toRun) == 0 { | ||
| return | ||
| } | ||
|
|
||
| var vers []string | ||
| for _, m := range toRun { | ||
| vers = append(vers, m.version) | ||
| } | ||
|
|
||
| lo.Fatalf(`there are %d pending database upgrade(s): %v. The last upgrade was %s. Backup the database and run --upgrade`, | ||
| len(toRun), vers, lastVer) | ||
| } | ||
|
|
||
| // getPendingMigrations gets the pending migrations by comparing the last | ||
| // recorded migration in the DB against all migrations listed in `migrations`. | ||
| func getPendingMigrations(db *sqlx.DB) (string, []migFunc, error) { | ||
| lastVer, err := getLastMigrationVersion(db) | ||
| if err != nil { | ||
| return "", nil, err | ||
| } | ||
|
|
||
| // Iterate through the migration versions and get everything above the last | ||
| // upgraded semver. | ||
| var toRun []migFunc | ||
| for i, m := range migList { | ||
| if semver.Compare(m.version, lastVer) > 0 { | ||
| toRun = migList[i:] | ||
| break | ||
| } | ||
| } | ||
|
|
||
| return lastVer, toRun, nil | ||
| } | ||
|
|
||
| // getLastMigrationVersion returns the last migration semver recorded in the DB. | ||
| // If there isn't any, `v0.0.0` is returned. | ||
| func getLastMigrationVersion(db *sqlx.DB) (string, error) { | ||
| var v string | ||
| if err := db.Get(&v, ` | ||
| SELECT COALESCE( | ||
| (SELECT value->>-1 FROM settings WHERE key='migrations'), | ||
| 'v0.0.0')`); err != nil { | ||
| if isTableNotExistErr(err) { | ||
| return "v0.0.0", nil | ||
| } | ||
| return v, err | ||
| } | ||
| return v, nil | ||
| } | ||
|
|
||
| // isTableNotExistErr checks if the given error represents a Postgres/pq | ||
| // "table does not exist" error. | ||
| func isTableNotExistErr(err error) bool { | ||
| if p, ok := err.(*pq.Error); ok { | ||
| // `settings` table does not exist. It was introduced in v0.7.0. | ||
| if p.Code == "42P01" { | ||
| return true | ||
| } | ||
| } | ||
| return false | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,27 @@ | ||
| package migrations | ||
|
|
||
| import ( | ||
| "github.com/jmoiron/sqlx" | ||
| "github.com/knadh/koanf/v2" | ||
| "github.com/knadh/stuffbin" | ||
| ) | ||
|
|
||
| // V2_0_0 performs the DB migrations. | ||
| func V2_0_0(db *sqlx.DB, fs stuffbin.FileSystem, ko *koanf.Koanf) error { | ||
| if _, err := db.Exec(` | ||
| CREATE TABLE IF NOT EXISTS settings ( | ||
| key TEXT NOT NULL UNIQUE, | ||
| value JSONB NOT NULL DEFAULT '{}', | ||
| updated_at TIMESTAMP WITH TIME ZONE DEFAULT NOW() | ||
| ); | ||
| CREATE INDEX IF NOT EXISTS idx_settings_key ON settings(key); | ||
| `); err != nil { | ||
| return err | ||
| } | ||
|
|
||
| if _, err := db.Exec(`ALTER TABLE entries ADD COLUMN IF NOT EXISTS meta JSONB NOT NULL DEFAULT '{}'`); err != nil { | ||
| return err | ||
| } | ||
|
|
||
| return nil | ||
| } |
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